Enlarge Microsoft's Courier was supposed to be an electronic journal or diary, a piece of hardware purpose-built for applications like OneNote. Two screens with a hinge between them, it opened and closed like a book, supporting both touch and stylus input on both its screens. Lenovo's new Yoga Book looks like a riff on the Courier combined with the company's successful range of 360 degree hinge Yoga-branded laptops. Like a Yoga machine, it's a more or less clamshell form factor that can be opened right up to turn it into a tablet of sorts.